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jump_search.py
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"""
Jump search algorithm
>>> arr = [
... 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610,
... ]
>>> arr[jump_search(arr, 55)]
55"""
Jump search algorithm
>>> arr = [
... 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610,
... ]
>>> arr[jump_search(arr, 55)]
55
>>> arr[jump_search(arr, 0)]
0
>>> arr[jump_search(arr, 610)]
610
Check if all arr at once:
>>> all(arr[jump_search(arr, x)] == x for x in arr)
True
"""
from math import floor, sqrt
def jump_search(arr, x):
prev = 0
n = len(arr)
step = int(floor(sqrt(n)))
while arr[min(step, n) - 1] < x:
prev = step
step += int(floor(sqrt(n)))
if prev >= n:
return -1
while arr[prev] < x:
prev = prev + 1
if prev == min(step, n):
return -1
if arr[prev] == x:
return prev
return -1
>>> arr[jump_search(arr, 0)]
0
>>> arr[jump_search(arr, 610)]
610
Check if all arr at once:
>>> all(arr[jump_search(arr, x)] == x for x in arr)
True
"""
from math import floor, sqrt
def jump_search(arr, x):
prev = 0
n = len(arr)
step = int(floor(sqrt(n)))
while arr[min(step, n) - 1] < x:
prev = step
step += int(floor(sqrt(n)))
if prev >= n:
return -1
while arr[prev] < x:
prev = prev + 1
if prev == min(step, n):
return -1
if arr[prev] == x:
return prev
return -1